Process of staining wood



F. T. ATKINSON. PROCESS OF STAINING WOOD.

APPLICATION FILED AUG. 14. 1919.

1,403,536. Patented Jan. 17, 1922.

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rannnnrcx THOMAS a'rxmson, on cmcnma'rr, 01110.

rnocrss or s'ramnie woon.

Application fllcd Aug-ust 14, 1919. Serial No. 317,609.

To all whom it may concern:

Be it known that I, Fnnnnnrcn THOMAS ATKINSON, a citizen of the United States, residing in Cincinnati, in the county of Hamilton and State of Ohio, have invented a new and useful Process of Staining Wood, of which the following is a specification.

My invention relates to the process of staining or coloring woods in imitation of other woods. and of staining or coloring sap wood or alburnum to correspond in color with the heart wood or duramen, and it has for its object the saving of waste, and a more natural, thorough, expeditious and cheaper process of staining wood.

In the drawing:

Fig. 1 represent a perspective inside elevation of a container, with one of the walls of the container removed, and having the wood arranged therein in a preferred position, for performing my improved process.

Fig. 2 is a perspective view of one of the pieces of wood, showing one end thereof in cross-section, and the other end thereof broken away.

There exists a necessity'for such a process because nearly all woods possess sapwood of a diiferent color from that of the heart wood and in some woodssuch as American black walnut,'wild cherry, butternut, birch, etc., the difl'er'ence between the color of the heart and the sap wood is so marked as to causethe sap wood to lose its value as a wood peculiar to its kind. Sap in most of the woods is considered a defect for the reason that its color differs from that of the heart wood, rather than for any other reason, excepting, perhaps, its'inferior durability when exposed to the inclemency of the weather. In order to utilize the sap wood in furniture, interior finish, etc., it is necessary to stain it to correspond in color with the heart wood. If'it is not stained, then it must be eliminated and becomes waste. For most practical purposes, the sap wood the sap as well as the heart wood, in addition to the enhancement of the value of the sag wood. 4

- he duramen or heart wood of the'various species of timber contains a coloring matter peculiar to its kind and when the of this coloring matter. It i soluble and forms a coloring liquid or solution.

The 'alburnum or sapwood is porous and by forcing this coloring liquid through the pores of the wood, the sap wood is stained Specification of Letters Patent. t t Jan. 17, 1 2

wood is put into liquid it gives up a portion corresponding to the color of the heart wood.

Heating the liquid sufliciently causes it to circulate more rapidly through the wood, and also causes the wood to give up more of its coloring matter. I discovered that a stain more nearly natural is acquiredby a quick rather than a slow process and that by performing the process a rapidly as pos-- sible it prevents the coloring matter from deteriorating and the color becomes identi-- cal with that of the heart wood. I also discovered that a forced circulation of the coloring liquid in the vessel or container also accelerates the coloring matter through the pores of the wood and that such a process produces a natural coloration without injury to the wood in any commercial sense.

By adding a fixing solution the'color bequires a longer time than it does when the coloring liquid is forced through the pores. For this reason when the wood is laid longitudinally in the vessel, the coloring liquid attempts to enter both ends of the pores at the same time, thus compressing the air and interfering with the circulation of the coloring liquid through the pores. I discovered that this could be overcome by maintaining a heavier pressure of the coloring liquid at one end of the boards than at the other; and further that bystanding the boards on'end the pressure at the bottom drive out the air at the top of the board and enables the work of staining to begin much earlier than by other methods. It

shortens the time required to properly stain the wood by producing a more rapid circulation of the coloring solution through the wood. I discovered that when using containers constructed of iron or steel, or in which there were any iron or steel pipes or other members when the coloring solution came into contact with. the iron or steel, certain elements in the coloring solution so acted upon the iron or steel that the coloring matter changed from the natural color to a foreign and unnatural color, and I further discovered that vitrified substances did not give up any elements in sufiicient quantities to injure the natural color of the coloring mat ter extracted from the wood or to be commercially injurious to the process of stain ing; that such substances as wood, wood fibre, and the various compounds manufac-. tured from wood and plant life, concrete, cement, vitrified clay, brick, sand, stone and their compounds, or any vitrified, nonmetallic or other substance which does not afford contact between the liquid and anyiron or steel, could be used satisfactorily for making the containers without injury to the coloring matter extracted from the. wood or injury to the process of staining; and if the container is constructed of iron or steel or their compounds it is advisable to line it with some non-metallic, vitrified or other substance which will prevent the coloring solution from substantially coming in contact with iron or steel.

A container, such as I prefer to employ, is shown at 11, and may consist of a body 12, for instance, of iron or steel, rovided with an nner lining 13 of a vitrifie substance, in which the wood, represented as pieces 14, are placed on end in a ody of liquid in th contamer, the level of which is shown at 24 as covering the wood, the ends of the wood being exposed to the liquid, and the wood retamed below the level of the top of the li uid, in suitable manner.

eart portions of the wood are exemplified at 17, and sap portionsof the wood are represented at 18, pores of the wood being reprresented at 19.

he *heat for the li uid may be obtained by steam forced into t e water, as through the nozzle 20 of an injector 21, which may be of wood. The force of the'injected steam will induce circulation of the liquid in the contained in the direction of the arrows 22 and induce a flow of the liquid in downward d rection toward the injector 20 through a pigs 23, which may also be or wood.

. y my lmproved process. woods containing continuous pores and possessing but little coloring matter can be stained or colored in imitation of other woods possessing strong coloring matter, such as poplar with walnut,

basswood with butternut, soft maple with cherry, etc. a

I attain these objects by my improvement in'the process of staining wood which consists of the following: A vessel or container that will hold a liquid should be com ,osed preferably of a non-metallic or vitrifie sub stance such, for example, as wood, woodfibre, concrete, cement, brick, stone or their compounds, such as vitrified clay, porcelain or any vitrified substance. However, iron or steel should not be used, either in the vessel itself or in any pipes or other members. If thevessel is of an iron or steel substance it should be lined with some non-metallic or other substance excepting iron or steel and noiron or steel substance should be exposed so that the liquid contents will be allowed to act upon it in such a way as to dissolve it. To get the best results it should be constructed so that it will withstand the adequate heating of the liquid contents. The lumber (both the wood to be stained and the wood from which the coloring is to be extracted) is put into the vessel and either stood on end or laid horizontally. If laid horizontally the liquid coloring matter hereinafter referred to should be caused to circulate in such a way as to produce a greater pressure against the lumber at one end than at the other. When stood on end the pressure produced by gravity supplies this requirement. When heat is employed and the wood is arranged with one end higher than the other, gravity is supplemented by the circulation of the liquid subjected to heat. Liquid 1s placed in the container for the purpose of extracting the coloring matter from the wood. This can be done before or after the wood is placed in the container, but the work is facilitated by adding the liquid after the wood is placed in the container. In'order to" facilitate the extraction of the coloring matter and to hasten the circulation ofthe colorin matter through the wood the liquid is so 'jected to heat and it is maintained 1n a heated condition until the sap wood'has become the same color as the'heart wood, or the wood to be stained has taken on the same color as the wood whose color it is sought to imitate. When the coloring or stain ng process has been comfpleted the coloring liquid may be drawn 0 and put in another vessel and kept for the next operat on. When the second and subsequent operatlons are started, instead of filling the. vessel with water the coloring solution of the previous 0 eration is put in and only enoug liquid added to keep the lumber submerged. Durin the process of staining care should be ta on not to prolong the operation unnecessarilybecause the coloring solution which I have also referred to as the liquid, has a tendency to deteriorate, and care should also be used not to raise the temperaturetoo high as it becomes injurious to the coloring solution andalso the wood.

The time required to properly complete the process of staining runsfrom two and a half to five days, depending upon the dryness of the lumber, and whether it is forest or field growth. Field growth usually takes longer than forest, and green woo takes longer that seasoned wood.' I obtained the best results by using a container made entirely of wood, with no nails or metals of any .kind exposed to contact with the coloring but all have certain objections. The method of staining by the usual dipping or by ap lication with a brush'is not satisfactory ecause the heart wood in the same kind of wood varies in color, thus necessitating a great variety of stains to produce the proper color. The stain does not penetrate the wood to any extent and an injury to the board revealsthe fact that what was supposed to be heart'wood is only an imitation.

The method of steaming is comparatively slow; It usually takes two or three weeks to complete the operation.- The coloring matter deteriorates and muchof the natural uality is lost or changed, thus producing a ull, unnatural color, rather than the nate ural, enlivening color eflfect. It kills the life of the wood; causes it to become brittle or brash and to break easily, and it destroys its usefulness for bending purposes.

. Aside from being commercially more economical my process produces none of. the

objectionable features mentioned. Onthe contrary, it can be completed, in much shorter time. It causes the gradation of color'from' the heart to the sap wood to be uniform and identical with the heart wood in color. The color has not the appearance of being artificial but has the natural, enlivening color effect. The sap wood in eacli board takes the same shade of color as the heart. wood in the same board, instead of coloring the sap wood of all the boards one color regardless of what maybe the shade of the heart wood in each particular board, The stain penetrates the entire board regardless of what may be its thickness so that the shade or color in one part of the board is the same as that in any other part of the board, whether sap or heart wood; It does not kill the life of the wood nor destroy its usefulness for bending purposes nor does it This furnished the forced injure its qualitiesfor polishing or interfere with any of its commercial values or quail; ities. It is considerably cheaper than other processes. I

' If desired, suitable coloring matter may be supplied to the liquidin addition to the color constituents extracted from the'wood as hereinbefore described.

I claim:

1. The method of treating wood to substantiall uniformly color the same, which consists 111 extracting color constituents from the darker portions of said wood and supplying color constituents so extracted to the lighter portions of said wood by subjecting said wood to the action of a liquid which transforms said color constituents, which liquid is substantially free of contact with iron and with steel. I

2. The method of treating wood to substantially uniformlycolor the same, which consists in extracting color constituents from the darker portions of said wood and supplying color constituents so extracted to the ighter portions of said wood by subjecting said wood to the forced circulation of a liquid which transfers said color constituents, which liquid is substantially free of contact with iron and with steel. 3. The method of staining wood, consisting of placing wood members in a container into which liquid is placed, and constructed so that the liquid contents thereof will. not be substantially subjected to contact with any iron and steel, heating the liquid to through the wood to be stained.

4. The method of staining wood, consist ing of placing wood members in a container having all parts which are exposed to liquid free from iron and from steel-,and containing water, heating the water 'andcausing a forced circulation of the liquid.

5. The method of stainiiigwood, consisting of lacing wood members and liquid in a vesse, heatin' the liquid, causing a circulation of the liquid through the wood, the -vessel so constructed as to preventelements in the liquid from acting chemically upon any iron and any steel used in'the construction of the vessel and in heating the liquid.

6. Themethod of treating wood to substantiall uniformly color the same, which consists inextracting colorconstituents from the darker portions of said wood and sup-' about 212 degrees Fahrenheit, and causing a forced circulation of the liquid thus heated.

plying color constituents so extracted to'the ighter portions ofsaid wood by subjectin I said woodto the pressure flow of a liqui which transfers said color constituents, which liq'uid is substantially free of contact with iron and with steel, and exerting said ressure flow lengthwise of the pores of the o0 Y .7."The method of treating wood to sub- I Stflfltlfllli uniformly color the same, which consists in subjectin wood having different shades of color to t e pressure of a liquid in the resence of heat, which liquid is sub- '5 stantia 1y free of contact with iron and with steel, said pressure exertedlengthwise of the pores of said wood, whereby to extract color FREDERICIQ THOMAS ATKINSON. 

